The high sensitivity door edge switch of the present invention is particularly concerned with safety edges and automatic stop switches for doors, such as overhead doors, public conveyance doors, wherein the door is automatically operated and it is desired to quickly, safely and reliably stop (and reverse, if required) door operation responsive to relatively low external pressure applied to the leading door edge, even if the external pressure is dispersed to effectively reduce its unit value. Of course, the instant door edge switch is capable of many varied applications, all of which are intended to be comprehended herein.
Illustrative of the prior art of which applicant is aware are the below listed patents:
______________________________________ U.S. Pat. No. Patentee ______________________________________ 3,243,540 Miller 3,462,885 Miller 3,754,176 Miller 4,090,045 Marsh 4,137,116 Miller 4,200,777 Miller 4,349,710 Miller 4,362,911 Sears 4,396,814 Miller ______________________________________
In prior art switches of this general type, there was required a highly localized deflection to operate the switch. Even a substantial force or weight may not have been sufficient to actuate a prior art switch, if the force or weight was distributed over a substantial area. In an attempt to obviate this problem, prior art devices often included internal protrusions for locally enhancing internal forces reacting to an external weight. This structure added to cost of materials, complexity of manufacture, and often inhibited or reduced flexibility to require additional space in shipping and storage.